1. Field of the Invention
The invention relates to a fuel cell system and, more particularly, to an art for removing an odorant from a mixed gas containing hydrogen gas and the odorant.
2. Description of the Related Art
A fuel cell generates electricity by means of hydrogen gas contained in a fuel gas and oxygen gas contained in an oxidative gas. A spent fuel gas (fuel off gas) and a spent oxidative gas (oxidative off gas) are discharged from the fuel cell.
In a fuel cell system, a mixed gas (fuel gas) containing hydrogen gas and an odorant is used to sense leakage of hydrogen gas at an early stage. However, the odorant often deteriorates output characteristics of the fuel cell. Hence, there has been devised a construction wherein an odorant removal portion for removing the odorant from the fuel gas is provided upstream of the fuel cell, more specifically, in a fuel gas passage through which the fuel gas flows. One such fuel cell system is disclosed, for example, in Japanese Patent Application Laid-Open No. 2002-29701.
In such a fuel cell system, however, leakage of hydrogen gas can be sensed only in a fuel gas passage region upstream of a fuel cell.